JP2584841Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system for an internal combustion engine, and more particularly to an improvement in spray characteristics in an engine having a fuel injection valve upstream of a swirl control valve.

[0002]

2. Description of the Related Art In recent years, there has been proposed a lean-burn engine in which combustion is performed at an air-fuel ratio (for example, 20 to 25) which is extremely higher than a stoichiometric air-fuel ratio for the purpose of improving fuel efficiency. In the above, a swirl control valve is provided to ensure ignition stability for a lean air-fuel mixture, and at the time of lean combustion, the swirl control valve is closed to generate a strong swirl in the cylinder, thereby stabilizing the ignition of the lean mixture. In some cases, the leanness has been improved and the lean burn limit has been improved.

[0003]

As the swirl control valve as described above, a butterfly type valve having a notch which is unevenly distributed is used, and when the valve is closed, the intake air flows only through the notch. In this case, a swirl is generated by causing the fuel injection valve to be provided, and the fuel injection valve is provided upstream of the swirl control valve.

That is, if the swirl control valve is closed during lean burn, much of the fuel injected from the upstream fuel injection valve hits the swirl control valve directly, causing a delay in fuel transport and accumulation of fuel. ,
In some cases, the air-fuel ratio controllability during the transient operation deteriorates, and the combustion stability deteriorates. Further, even when the swirl control valve is opened, depending on the positional relationship of the swirl control valve with respect to the spray direction of the injection valve, a large amount of fuel may directly hit the swirl control valve, causing a similar problem.

As described above, conventionally, the spray characteristics of the fuel injection valve have not been properly set in consideration of the influence of the provision of the swirl control valve. The interference had a negative effect on the formation of gas. The present invention has been made in view of the above circumstances, and in an internal combustion engine equipped with a swirl control valve having a notch downstream of the fuel injection valve, the interference between the fuel spray and the swirl control valve is appropriately set, and the swirl is set. Avoiding the delay in fuel transport by the control valve, improving the air-fuel ratio controllability during engine transient operation,
The aim is to improve the mixture formation.

[0006]

Therefore, in the fuel injection device for an internal combustion engine according to the present invention, a butterfly type swirl control valve having a notch is provided in an intake system downstream of the fuel injection valve, and the swirl control valve is mounted on the engine. A fuel injection device for an internal combustion engine having a configuration in which opening and closing are controlled in accordance with operating conditions, and swirl is generated in a cylinder by flowing intake air only through the cutout portion with the swirl control valve closed. the spray direction of the fuel injection valve, Rutotomoni toward the notch of the swirl control valve in the closed state, the swirl control bar
In the lube closed state, the fuel is injected from the fuel injection valve.
A part of the fuel spray is swirl-con
Configured to hit the trawl valve directly and swirl
When the control valve is open, the fuel spray
The direct hit rate for the swirl control valve is reduced to almost 0
It was configured so that:

[0007]

According to the action Such construction, when the swirl control valve is closed, the fuel toward the notch of the swirl control valve is injected, this time retardant
A part of the fuel spray injected from the fuel injection valve
Hit the swirl control valve directly within the rate range . Therefore, it is possible to promote the atomization and vaporization of the air-fuel mixture by directly hitting to some extent while avoiding the delay of fuel transport caused by the excessive hitting rate.

Further, when the swirl control valve is in the open state, the direct hit rate against the swirl control valve is low.
Since it is substantially zero, there is no delay in transporting fuel even in the open state, and it is possible to avoid adverse effects such as a change in spray direction due to unnecessary interference.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram mainly showing an intake system of the internal combustion engine provided with the fuel injection device according to the present invention.
, Air is sucked in through a throttle valve 2, an intake manifold 3 and an intake valve 4.

In each branch of the intake manifold 3, a fuel injection valve 5 is provided for each cylinder. The fuel injection valve 5 is an electromagnetic fuel injection valve that is energized by a solenoid and opens, and is deenergized and closed by being energized by an injection pulse signal from a control unit 16 to be described later. Fuel that is pressure-fed from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator is injected and supplied to the engine 1.

An ignition plug 6 is provided in each combustion chamber of the engine 1 to ignite a mixture by spark ignition. Then, exhaust gas is discharged from the engine 1 through an exhaust valve 7, an exhaust manifold 8, an exhaust duct 9, and a catalyst 10. The control unit 11 includes a CPU, ROM, RA
A microcomputer including an M / A / D converter, an input / output interface, and the like is provided. The microcomputer receives input of detection signals from various sensors and generates engine mixture air having a predetermined target air-fuel ratio. Basic fuel injection amount T corresponding to the amount
p, and various corrections are made to the basic fuel injection amount Tp to calculate the fuel injection amount Ti.
The operation of the fuel injection valve 5 is controlled based on.

In this embodiment, a map is provided in which the target air-fuel ratio is stored according to the engine load and the engine speed. In the target air-fuel ratio map, a predetermined low load
In the low rotation region, a lean air-fuel ratio (for example, 20 to 25) that is extremely higher than the stoichiometric air-fuel ratio (14.7) is set as the target air-fuel ratio, and in a high load / high rotation operation region other than the lean combustion operation region. The stoichiometric air-fuel ratio or an air-fuel ratio slightly smaller than the stoichiometric air-fuel ratio (for example, an output air-fuel ratio of about 13) is set as the target air-fuel ratio.

Here, in order to ensure ignition stability in the low-load, low-speed lean combustion region, the engine 1 of the present embodiment is provided with a fuel injection valve 5 at each intake port of the intake manifold 3. Downstream, swirl control valves (hereinafter abbreviated as SCVs) 12 are interposed. The SCV 12 is, as shown in FIG. 2, a butterfly type throttle valve having a notch unevenly distributed.
By closing 12 and allowing the intake air to flow only through the notch, a high-velocity flow is swirled into the cylinder (lateral vortex).
Is generated, whereby the ignition stability at the time of lean combustion can be improved.

A diaphragm 13 is provided as an actuator for driving the SCV 12 to open and close, and the introduction of an engine negative pressure into the pressure chamber of the diaphragm 13 is controlled by an electromagnetic three-way switching valve 14 to control the SCV.
V12 can be opened and closed. The control unit 11 controls the three-way switching valve 14 so as to close the SCV 12 in the lean fuel region in the target air-fuel ratio map and to open the SCV 12 otherwise.

It should be noted that a motor may be used as an actuator for driving the SCV 12 to open and close. Here, the engine 1 of this embodiment has a configuration in which the intake port is divided into two branches and extends downstream of the SCV 12 to face the cylinders. The air-fuel mixture is sucked inside.

As shown in FIG. 2, the fuel injection valve 5 is a two-way injection valve that injects fuel toward each intake port that is divided into two at the downstream side. As shown in FIG. 1 and FIG. 2, it is directed to each intake valve and to the notch 12a of the SCV 12 in the closed state. That is, in the closed state of the SCV 12, the fuel injected from the fuel injection valve 5 is set so as to pass through the notch 12a of the SCV 12 and directly hit the intake valve 4, whereby the fuel is injected into the cylinder. It turns with the swirl flow to promote stratified combustion.

Here, when passing through the notch 12a of the SCV 12, the fuel spray does not pass without directly hitting the SCV 12 at all.
The peripheral portion of the fuel spray directly hits the SCV12 at a low direct hit rate. As shown in FIG. 4, if the direct hit rate is excessive and the setting is such that most of the injected fuel hits the SCV 12 directly, the fuel transport delay that cannot be fully corrected by the fuel correction during the transient operation will be reduced. Therefore, it is necessary to keep the direct hit rate low.

However, the fuel spray is sprayed to a certain degree
Directly hitting the V12 promotes atomization and vaporization of the fuel.
It is desired that the vehicle be hit directly to some extent within the range where the transport delay does not occur. In particular, when lean combustion is performed when the SCV 12 is closed as in the present embodiment, if the fuel is atomized when passing through the SCV 12 with an appropriately set direct hit rate, swirl enhancement by the SCV 12 can be performed. Together, it can contribute to the formation of a good air-fuel mixture, thereby making it possible to improve the lean burn limit.

Therefore, in the present embodiment, the direct impact rate in the closed state of the SCV 12 is set to be a low direct impact rate within a range of 10% to 30% to avoid the occurrence of fuel transport delay during transient operation. While using SCV12, atomization of fuel can be promoted. In the open state of the SCV 12, the fuel injected from the fuel injection valve 5 reaches the intake valve 4 directly without almost directly hitting the SCV 12 (direct hit rate ≒ 0%).

When the SCV 12 is closed, the SCV 12 is substantially perpendicular to the main axis of the fuel spray, and the fuel directly hitting the SCV 12 is atomized and rebounds to the upstream side. It is drawn into the main flow passing through the notch 12a and is injected together with the intake valve 4. On the other hand, when SCV12 is open,
The SCV12 is arranged obliquely with respect to the main axis of the fuel spray. Even if the SCV12 in this state is directly hit with the fuel, a large atomization effect cannot be obtained, and the fuel spray is directed by colliding with the SCV12. May be changed.

For this reason, as described above, when the SCV 12 is in the open state, the fuel injected from the fuel injection valve 5 almost loses the SCV 12.
The vehicle is passed without hitting directly (at a direct hit rate of about 0) . In this embodiment, each cylinder is provided with two intake ports, and the fuel injection valve 5 provided at the junction of the two intake ports performs two-way injection in accordance with this. May have a single intake port, and the fuel injection valve 5 may perform a one-way injection.

[0022]

As described above, according to the present invention, in an internal combustion engine in which a fuel injection valve is provided upstream of a swirl control valve, fuel transport delay due to a large amount of fuel directly hitting the swirl control valve. Can be avoided, thereby improving the air-fuel ratio controllability at the time of transition, and promoting the atomization of fuel by an appropriate amount of direct impact on the swirl control valve in the closed state,
For example, in an engine that performs lean burn by closing the swirl control valve, there is an effect that the lean burn limit can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a state of fuel spray of an embodiment.

FIG. 2 is a front view showing a state of fuel spray of the embodiment.

FIG. 3 is a system diagram showing the overall configuration of the engine according to the embodiment.

FIG. 4 is a diagram for explaining an appropriate direct hit rate.

[Explanation of symbols]

 Reference Signs List 1 engine 2 throttle valve 3 intake manifold 5 fuel injection valve 11 control unit 12 swirl control valve (SCV) 12a notch 13 diaphragm 14 three-way switching valve 16 control unit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Nakamura 1671-1, Kasukawa-cho, Isesaki-shi, Gunma Japan Electronic Equipment Co., Ltd. (72) Inventor Toru Sakuma 1671-1, Kasukawa-cho, Isesaki-shi, Gunma Japan Electronic equipment stock In-house (72) Inventor Yoshito Ino 1671-1, Kasukawa-cho, Isesaki-shi, Gunma Japan Electronic Equipment Co., Ltd. (72) Inventor Hideo Kato 1671-1, Kasukawa-cho, Isesaki-shi, Gunma Japan In Electronic Equipment Co., Ltd. (56) References JP-A-5-231276 (JP, A) JP-A-5-231275 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 69/00 F02M 69/04 F02B 31 / 02 F02M 29/00 F02M 29/04

Claims (1)

(57) [Scope of request for utility model registration] A butterfly swirl control valve having a notch is provided in an intake system downstream of a fuel injection valve,
Fuel injection for an internal combustion engine having a configuration in which the swirl control valve is controlled to open and close according to engine operating conditions, and in a closed state of the swirl control valve, swirl is generated in the cylinder by flowing intake air only through the notch. an apparatus, the spray direction of the fuel injection valve, Rutotomoni toward the notch of the swirl control valve in the closed state, swirling
When the control valve is closed, the fuel injection
Part of the fuel spray injected from the valve is within the specified low direct hit rate range
Configured to hit the swirl control valve directly within
And the swirl control valve is open
Corresponds to the swirl control valve of the fuel spray.
Wherein the direct impact rate is substantially zero .